[–] WhatWouldOdinDo 0 points 1 point 1 point (+1|-0) ago (edited ago)
Ceramic logs are meant to disperse heat on a gas fire fixture. The most common form of these I've seen are "fire rocks" which are just lumps of ceramic material. Without something like this most of the heat from a propane fixture just goes up and doesn't heat the environment, which is what you would want from an outdoor fire pit like this.
It also fans the flame out providing a better visual element than just a tall standing flame.
Also, you could use these with a wood fire, but they would get pretty dirty.